A Sidman avoidance conditioning schedule is one in which an animal receives an aversive stimulus (eg a mildelectric shock) at regular fixed intervals (eg 10 secs), without a warning signal, unless it performs an avoidance response (eg crossing a barrier, pressing a lever.). After each avoidance response the timer is reset so the avoidance behaviour earns the animal a timed respite as the shock is delayed for set amount of time (eg 20 secs.).

There are therefore two independent temporal variables in the procedure which can be manipulated:

Shock-shock interval, (S-S)

Response-shock interval (R-S)

In this procedure animals typically learn to avoid the shocks and can demonstrate very accurate timings of their response.

Behavior can be explained as a molecular function of the S-S and R-S relationships or as a molar function of the overall rate of punishment. The molar explanation of avoidance behavior tends to be more supported by research.

Murray Sidman developed the use of the procedure in the 1960s. It is also known as temporal avoidance conditioning or free operant avoidance conditioning